Sunday 6 December 2015 13.21 EST
First published on Sunday 6 December 2015 12.30 EST

Former US president Jimmy Carter announced that he was cancer-free on Sunday, just four months after revealing that doctors had found four spots of melanoma on his brain.

“My most recent MRI brain scan did not reveal any signs of the original cancer spots nor any new ones,” Carter said in a statement on Sunday. “I will continue to receive regular three-week immunotherapy treatments of pembrolizumab,” he added, referring to a common cancer drug.

Carter, 91, shared the news on Sunday with worshippers at the Baptist church in Georgia where he teaches Bible study. The news was confirmed by two grandsons.

In a video published by NBC News, Carter said: “I went to the doctors this week for the second time. The first time I went for an MRI of my brain, the four places were still there but they were responding to the treatment. And when I went this week, they didn’t find any cancer at all. So I have good news.”

Carter smiled slightly as people in the congregation responded with applause. “So a lot of people prayed for me and I appreciate that,” he said.

In August, the former president convened a press conference to announce that he had cancerous growths on his brain. He said the cancer, a form of melanoma, was likely to “show up in other places in my body” and that he was embarking on months of radiation treatments and injections to combat its spread.

Carter, the 39th president, told the Baptist congregation that no such spread had occurred in news first reported by the Atlanta Journal-Constitution.

“He said he got a scan this week and the cancer was gone,” the paper quoted Carter’s friend and fellow churchgoer Jill Stuckey as saying in a phone call from the Maranatha Baptist Church in Plains, where Carter grew up and still lives. “The church, everybody here, just erupted in applause.”

“Victory!” tweeted grandson James Carter IV, with a link to the Journal-Constitution’s coverage.

Associated Press quoted Stuckey as saying: “Our prayers have been answered. I can’t think of a better Christmas present.”

A second grandson, Jason Carter, told the agency in a text message that his grandfather “told me that the doctors couldn’t find any cancer in his most recent scan”.

When he announced the diagnosis in August, the former president’s outlook did not appear so rosy. His entire nuclear family from childhood – two sisters, a brother and both parents – died from cancer. Carter said he had been diagnosed with melanoma on his liver and that he had told his wife of 69 years, Rosalynn, 88, months earlier.

An operation to remove growths on his liver had discovered the additional growths on his brain, Carter said in an appearance at the Carter Center, the foundation hosted at Emory University out of which the former president conducts his international charity and human rights work.

“They did an MRI and found that there were four spots of melanoma on my brain,” Carter said. “They are very small spots, about two millimeters if you can envision what a millimeter is, and I’ll get my first radiation treatment for the melanoma in my brain this afternoon.

“I was surprisingly at ease,” the former president said in reply to a reporter’s question. “I’ve had a wonderful life ... I’ve had an exciting, gratifying existence. I felt surprisingly at ease, much more than my wife was. But now I feel it’s in the hands of God, and I’ll be prepared for what comes. I’m looking forward to a new adventure.”

In November, Carter told the AP he had reacted well to treatment. “I haven’t been uncomfortable or ill after the treatments were over. So that part of it has been a relief to me and I think to the doctors. But the final result of how well the treatments are combatting or controlling the cancer, we don’t know yet.”

Carter has maintained an active public schedule through his cancer treatment. Last month, he participated in a house-raising project in Tennessee with the charity Habitat for Humanity, which he accompanies each year to Nepal for similar projects.

Carter has lived 34 years post-presidency, longer than any of his peers. Both presidents Gerald Ford and Ronald Reagan lived to be 93 while former president George HW Bush turned 91 in June.

Dr Len Lichtenfeld, the deputy chief medical officer for the American Cancer Society, said doctors evaluating melanoma patients would use scans of other body parts beyond where the disease has been found to ensure it has not spread.

“For today, the news cannot be better,” Lichtenfeld told the Associated Press. “Circumstances may change over time or he may be in a situation where it does not recur for many years or at all.”

He said he expected that Carter’s doctors would continue “close surveillance” for any new cancer growth or recurrence in his brain and continue doses of the immunotherapy drug as long as Carter handles it well.